Security elements and chromophoric security features

ABSTRACT

The invention relates to a system, security elements and security features with colour effects, which can be produced by vapour deposition in a PVD or CVD process, processes for their production and their use.

The invention relates to a system, security elements and securityfeatures with colour effects, which can be produced by vapour depositionin a PVD or CVD process, processes for their production and their use.

Data carriers and valuable documents, such as banknotes, identity papersor the like, or packaging materials for sensitive goods such aselectronic components, pharmaceutical products and the like are providedwith security elements, for example in the form of threads, strips,tapes, patches or other formats, in order subsequently to be able tocheck their authenticity. The information and codes, for exampleelectrical conductivity, magnetic codes, holograms or diffractionstructures, symbols, patterns, cutouts, coloured and/or luminescenteffects or sequences and the like possessed by the security features areincreasingly becoming more complex and more expensive in order toachieve increased security against forgery and making exact copyingvirtually impossible.

However, the complex information, codes and the like possessed by thesecurity features are generally difficult to detect optically or theability to detect them optically or check them is not desired. Normally,the security features can only be read expensively by a machine and inthis way the authenticity of the corresponding data carrier, thevaluable document or the packs can be checked.

However, it is often advantageous to apply an additional opticallyunambiguous and detectable feature to the data carrier, the valuabledocument or the pack, which is not only used as a possibly additionalsecurity feature but also permits an unambiguous assignment of the datacarrier, valuable document or the pack, for example to a specific placeof origin, a specific value or a specific content, a specific brand orthe like.

It was an object of the invention to propose a system of securityelements which, if appropriate, in addition to the codes and elementsdescribed above, permits a specific defined property to be allocated toa data carrier, a banknote or the like by means of a specific colouredeffect which can be detected easily.

The object of the invention is, therefore, a system for the opticallysimply detectable and unambiguously assignable identification of datacarriers, valuable documents and/or packs and the like, characterized inthat the data carrier, the valuable document and/or the pack is providedwith a full-area or partial coating which, by means of its coloration orby means of the colour effect produced and/or by means of its dimensionand/or situation and/or its structure, permits an unambiguous assignmentof the data carrier, of the valuable document and/or of the pack to adefined property.

A further object of the invention is security elements to be applied toand/or at least partly embedded in data carriers, valuable documentsand/or packs and the like, characterized in that the security elementsare provided with a coating which, by means of its coloration or bymeans of the colour effect produced and/or by means of its dimensionand/or situation and/or its structure, permits an unambiguous assignmentof the data carrier, of the valuable document and/or of the pack to adefined property.

A further object of the invention is a thin sheet material,characterized in that it is provided with a coating which, by means ofits coloration or by means of the colour effect produced respectivelyand/or by means of its dimension and/or situation and/or its structure,permits an unambiguous assignment to a defined property.

The system according to the invention comprises security elements havinga defined coloured, if appropriate also metallic or apparently metallicor reflective, coating which, by means of the different colour effects,permits an unambiguous assignment of the data carrier, of the valuabledocument and/or of the pack to a defined property

Thus, for example, a security element corresponding to the invention,which is provided with such a coating with different colour effects as asecurity feature, can be applied to valuable documents in accordancewith their value and/or at least partly embedded in the said documents.

The hue or the colour effect produced by the coating then permits anunambiguous assignment to the value of the valuable document.

In this case, it is possible, for example depending on the value of abanknote, to use different colours or colour effects or else, forexample within a banknote series, different graduations or intensitiesof the same colour.

Furthermore, colour matching of the coating to the colour of thebanknote can be carried out.

In the case of packs, this defined colour effect can, for example,identify the content and/or the place of origin of the productunambiguously.

The coating can additionally have further features, for example cutoutsin the form of patterns, symbols, lines, guilloches and the like.Furthermore, the coating can be present as a solid tone, in half-tone,or rastered.

Furthermore, the coating according to the invention can be combined withfurther layers having functional and/or decorative features, for examplelayers having magnetic and/or conductive properties, layers havingoptically active structures, for example surface reliefs, diffractiongratings and/or holograms.

The coating with the abovedescribed defined colour effect can be presentover the entire area or partially and is preferably applied to a carriersubstrate by means of a PVD or CVD process.

In this case, a carrier substrate, which can already have one or morestructured or unstructured layers, is treated by means of an in-lineplasma, corona or flame process and the coating according to theinvention is then applied either in-line or in a subsequent process stepin a PVD or CVD process.

The carrier substrate is preferably treated by means of an in-lineplasma (low pressure or atmospheric plasma), corona or flame process. Bymeans of a high-energy plasma, for example an Ar or Ar/O₂ plasma, thesurface is cleaned of any scumming residues which may be present. Inthis case, for a partial application, the necessary sharp delimitationof the contours of the cutout, which is needed for the necessaryprecision of decoding, is also achieved. In the process, polar groupsstanding on end are produced at the surface. This improves the adhesionof metals and the like to the surface.

If appropriate, at the same time as the application of the plasma orcorona or flaming treatment, a thin metal or metal oxide layer can beapplied as an adhesion promoter, for example by means of sputtering orvapour deposition. In this case, Cr, Al, Ag, Ti, Cu, TiO₂, Si oxides orchromium oxides are particularly suitable. This adhesion promoting layergenerally has a thickness of 0.1 nm-5 nm, preferably 0.2 nm-2 nm,particularly preferably 0.2 to 1 nm.

As a result, the adhesion of the partial or full-area coatings isimproved further.

Metals and their compounds, for example oxides, sulphides, or alloys,are particularly suitable.

Suitable metals are, for example, Al, Cu, Fe, Ag, Au, Cr, Ni, Zn, Cd, Biand the like. Suitable as metal compounds are, for example, oxides orsulphides or chromates of metals, in particular TiO₂, Cr oxides, ZnS,ITO, Bi oxide, ATO, FTO, ZnO, Al₂O₃, Zn chromate, Fe oxides, CuO and thelike or silicon oxides. Suitable alloys are, for example, Cu—Al alloys,Cu—Zn alloys, iron alloys, steel, for example Cr—Ni steel and the like.

If appropriate, the vapour-deposited metal compounds can also be dopedwith rare earth metals. As a result, in addition to the desired colour,a luminescence effect is additionally obtained. Furthermore, forexample, copper colour pigments, such as azurite or malachite, can bevapour-deposited.

The layer thickness of the vapour-deposited layer substantially dependson the desired colour. For example, a Bi oxide layer about at least160-230 nm thick, and also a TiO₂ layer appears transparent blue, a ZnSlayer appears green, a Cd layer appears yellow, an Al layer inconjunction with Fe₂O₃ appears orange to purple-red, the hue beingcontrolled by the input of energy. If Cu is vapour-deposited underexcess oxygen, the coating appears blue. Vapour-deposited ZnO appearstransparent and reddish.

The coating is applied in a PVD or CVD process. In a PVD process, thecoating is deposited on the carrier substrate under a vacuum (up to 10³¹¹² mbar, preferably 10⁻² to 10⁻⁶ mbar) at a temperature which depends onthe vapour pressure and the thickness of the coating to be applied, forexample by means of thermal vapour deposition, arc or electron beamvapour deposition. One further possibility is to apply the coating bymeans of AC or DC sputtering, the appropriate process being selected onthe basis of the layer to be applied and the material used. If aplurality of layers are to be applied, separating layers, for exampleinsulators, polymer layers and the like, can be applied between theindividual layers, in-line or in a separate process step.

In a CVD process, by mixing the substance to be applied with a gasplasma or with an activation gas, for example CO, CO₂, oxygen, silanes,methane, ammonia and the like, a chemical reaction is brought about bymeans of an ion beam and the substance produced is deposited on thecarrier. In this way, a plurality of reactive layers can be appliedsimultaneously or in parallel, a colour effect is produced on thecarrier substrate.

If the coating is to be applied partially to the carrier substrate, in afirst step, an applied colour that is soluble in a solvent is applied toone or both sides of the carrier substrate, in a second step, this layeris treated by means of an in-line plasma, corona or flame process and inthe third step, the coating is applied by means of a PVD or CVD process,whereupon, in a fourth step, the applied colour is removed by means of asolvent, possibly combined with a mechanical action.

The application of the applied colour can be carried out by means of anydesired process, for example by means of gravure printing, flexographicprinting, screen printing, digital printing and the like. The colourused or the colour varnish used is soluble in a solvent, preferably inwater, but a colour that is soluble in any desired solvent, for examplein alcohol, esters and the like, can also be used. The colour or thecolour varnish can be conventional compositions based on natural orartificial macromolecules. The soluble colour can be pigmented ornon-pigmented. All known pigments can be used as pigments. Particularlysuitable are TiO₂, ZnS, kaolin and the like.

The treatment already described above by means of an in-line plasma (lowpressure or atmospheric plasma), corona or flame process and theapplication of the coating is then carried out.

The coloured layer is then removed by a suitable solvent, which ismatched to the composition of the coloured layer. The applied colour ispreferably water-soluble. If appropriate, the solution can be assistedby mechanical action.

In order to improve the initial dissolving of the covered coloured layerfurther, a thin pigmented coloured layer or a pure pigment layer canalso be applied over the entire area or in register, the thickness ofthis layer being about 0.01-5 μm.

As a result of dissolving the applied colour with the regions of thecoating located over the applied colour, the desired partial coating isobtained.

Suitable as a carrier substrate for the security feature according tothe invention are, for example, carrier films, preferably flexibleplastics films, for example of PI, PP, MOPP, PE, PPS, PEEK, PEK, PEI,PSU, PAEK, LCP, PEN, PBT, PET, PA, PC, COC, POM, ABS, PVC. The carrierfilms preferably have a thickness of 5-700 μm, preferably 5-200 μm,particularly preferably 5-50 μm.

Dyed, colour-varnished or demetallized plastic films with colour effectscan also be used as the carrier substrate.

Furthermore, metal foils, for example Al, Cu, Sn, Ni, Fe orstainless-steel foils with a thickness of 5-200 μm, preferably 10 to 80μm, particularly preferably 20-50 μm, can be used as a carriersubstrate. The foils can also be surface treated, coated or laminated,for example to plastics, or varnished.

Furthermore, paper or composites with paper, for example, compositeswith plastics with a grammage of 20-500 g/m², preferably 40-200 g/m²,can be used as carrier substrates.

Furthermore, fabrics or nonwovens, such as endless fibre nonwovens,staple fibre nonwovens and the like, which may possibly be needled orcalendered, can be used as carrier substrates. Such fabrics or nonwovenspreferably consist of plastics, such as PP, PET, PA, PPS and the like,but fabrics or nonwovens of natural, possibly treated fibres, such asviscose fibre nonwovens, can also be used. The fabrics or nonwovens usedhave a grammage of about 20 g/m² to 500 g/m². If appropriate, thefabrics or nonwovens can be surface-treated.

However, the carrier substrate can also already additionally have avarnish or coloured layer, which can be unstructured or structured, forexample embossed. The varnish layer can, for example, be a transfervarnish layer with release properties, it can be cross-linked orcross-linkable by means of radiation, for example UV radiation, and canbe finished in a scratch-resistant and/or antistatic manner. Bothaqueous and solid varnish systems are suitable, in particular includingvarnish systems based on polyester acrylate or epoxy acrylate,colophony, acrylate, alkyd, melamine, PVA, PVC, isocyanate, urethanesystems, which can be conventionally or reactively curing (mixture orradiation curing).

In each case, an extremely wide range of compositions can be used as thecolour or varnish layers. The composition of the individual layers canvary, in particular in accordance with their task, that is to saywhether the individual layers are to serve only decorative purposes orare to be a functional layer or whether the layer is to be both adecorative and a functional layer.

These layers can be pigmented or non-pigmented. The pigments which canbe used are all known pigments, such as titanium dioxide, zinc sulphide,kaolin, ITO, ATO, FTO, aluminium, chromium and silicon oxides and alsocoloured pigments. In this case, varnish systems containing solvent andalso systems without solvent can be used.

Various natural or synthetic binders are suitable as binders.

These further functional layers, already present on the carriersubstrate or applied subsequently, can, for example, have specificchemical, physical and also optical properties.

The optical properties of a further layer may be influenced by visibledyes or pigments, luminescent dyes or pigments which fluoresce orphosphoresce in the visible, in the UV range or in the IR range, oreffect pigments, such as liquid crystals, pearl lustre, bronzes and/ormultilayer colour-change pigments and heat-sensitive colours orpigments. These can be used in all possible combinations. In addition,phosphorescent pigments can also be used on their own or in combinationwith other dyes and/or pigments.

Furthermore, electrically conductive layers can also be present on thesubstrate or applied subsequently, for example electrically conductivepolymer layers or conductive colour or varnish layers.

In order to adjust the electrical properties, the colour to be appliedor the varnish to be applied can have added to it, for example,graphite, carbon black, conductive organic or inorganic polymers, metalpigments (for example copper, aluminium, silver, gold, iron, chromiumand the like), metal alloys such as copper-zinc or copper-aluminium orelse amorphous or crystalline ceramic pigments such as ITO, ATO, FTO andthe like. Furthermore, doped or non-doped semiconductors such assilicon, germanium, or doped or non-doped polymer semiconductors or ionconductors such as amorphous or crystalline metal oxides or metalsulphides can be used as an additive. Furthermore, in order to adjustthe electrical properties of the layer, polar or partially polarcompounds such as surfactants, or non-polar compounds such as siliconeadditives or hygroscopic or non-hygroscopic salts can be used or addedto the varnish.

As a layer with electrical properties, a full-area or partial metallayer can also be applied, it being possible for the partial applicationto be carried out by means of an etching process (application of afull-area metal layer and subsequent partial removal by etching) or bymeans of a demetallization process.

If a demetallization process is used, in a first step, a colour that issoluble in a solvent (if appropriate in the form of an inverse code) ispreferably applied, and then, if appropriate following activation of thecarrier substrate by means of a plasma or corona treatment, the metalliclayer is applied, after which the soluble colour layer is dissolved bymeans of treatment with a suitable solvent, together with themetallization present in these regions.

Furthermore, an electrically conductive polymer layer can also beapplied as an electrically conductive layer. The electrically conductivepolymers can be, for example, polyaniline or polyethylenedioxythiophene. PEDT/TS is particularly preferably used as anelectrically conductive polymer.

It is also possible to add carbon black or graphite, for example, to themagnetic colour used, by which means a layer which is simultaneouslymagnetic and also electrically conductive can be produced particularlyadvantageously in a defined coding in accordance with the method of theinvention.

Furthermore, further surface relief structures, for example diffractiongratings, holograms and the like, are suitable as additional securityfeatures, it being possible for these structures, if appropriate, alsoto be metallized or partially metallized.

In order to produce surface structures of this type, first of allUV-curable varnish which can be deep drawn is applied. Then, forexample, a surface structure can be produced by moulding a female die inthis varnish which, at the time of the moulding, has pre-cured as far asthe gel point, the radiation-curable varnish then being cured completelyfollowing the application of the surface structure.

As a result of the use of the UV-curable varnish, following the curingof layers applied thereto, a surface structure which may possibly beintroduced is also stable even under temperature stress.

The radiation-curable varnish can be, for example, a radiation-curablevarnish system based on a polyester, an epoxy or polyurethane systemwhich contains two or more different photo initiators familiar to thoseskilled in the art which, at different wavelengths, are able to initiatecuring of the varnish system to a different extent. For example, a photoinitiator can be capable of activation at a wavelength of 200 to 400 nm,the second photo initiator then at a wavelength of 370 to 600 nm. Asufficient difference should be maintained between the activationwavelengths of the two photo initiators in order that excessively highexcitation of the second photo initiator does not take place while thefirst is being activated. The range in which the second photo initiatoris excited should lie in the transmission wavelength range of thecarrier substrate used. For the main curing (activation of the secondphoto initiator), electron radiation can also be used.

The radiation-curable varnish used can also be a varnish which can bediluted with water. Varnish systems based on polyester are preferred.

Furthermore, the coating according to the invention can additionally becombined with a layer which brings about a colour tilting effect, itthen being possible for the coating to function as a layer that reflectselectromagnetic waves.

In this case, the coating bringing about the colour tilting effect ineach case has at least one layer that reflects electromagnetic waves, aspacer layer (for example one or more polymer layers) and a layer formedof metallic clusters. A partial or full-area layer that reflectselectromagnetic waves, for example the coating according to theinvention, and then one or more partial and/or full-area polymer layersof defined thickness are applied to the carrier substrate. Applied tothis spacer layer is a layer formed of metallic clusters, which isproduced by means of a vacuum process or from solvent-based systems.

Furthermore, the security elements or thin sheet materials according tothe invention can be provided with a protective varnish layer on one orboth sides. The protective varnish can be pigmented or non-pigmented, itbeing possible for all known pigments or dyes, for example TiO₂, ZnS,kaolin, ATO, FTO, aluminium, chromium und silicon oxides or, forexample, pthalocyanine blue, i-indolide yellow, dioxazine violet to beused as pigments. Furthermore, luminescent dyes or pigments whichfluoresce or phosphoresce in the visible, in the UV range or in the IRrange, effect pigments such as liquid crystals, pearl lustre, bronzesand/or multilayer colour-change pigments and heat-sensitive colours andpigments can be added. These can be used in all possible combinations.In addition, luminescent pigments can also be used on their own or incombination with other dyes and/or pigments.

Furthermore, the security element according to the invention can beprovided on one or both sides with a hot-melt or cold-seal adhesive or aself-adhesive coating for application to or embedding in a substrate, itbeing possible for these adhesives or adhesive coatings to be pigmented.

Furthermore, the security element according to the invention can belaminated with one or more carrier substrates which, if appropriate,have functional and/or decorative layers, using a lamination adhesive,it being possible for the lamination adhesive also to be pigmented.

It is possible to combine the system according to the invention incombination with further security features, if appropriate at anotherpoint on the valuable document or the pack.

For example, the combination with an at least partly embedded securitythread which, for example, has positive or negative cutouts, isconceivable.

In one embodiment, the security element according to the invention isapplied in accurate register with the feature or features located in thecarrier, for example lines, cutouts, optical, electrical, magnetic oroptically active structures and the like, so that the security featureslocated on the security element form a complete authenticity oridentification feature only after application to or incorporation in thecarrier. Furthermore, by means of the above described accurate-registerapplication or incorporation of the security element, a continuation orrepetition of the security feature already present on the carrier can becarried out, which means that unambiguous checking of the authenticityor identity can be carried out.

The system according to the invention can be used as an easilydetectable security feature for authenticity or identification featureon data carriers, in particular valuable documents, such as identitypapers, and cards, banknotes, to packaging materials in thepharmaceutical, electronic or foodstuffs industry

In the case of packs, advantageously both the pack and the productpacked therein and, if appropriate, information packed with it, such astechnical data sheets, instructions for use, fitting instructions andthe like, are provided with a coating having a defined colour effect. Asa result, both the intactness of the pack and also any possiblemanipulation of the contents of the pack can be determined.

1. System for the optically simply detectable and unambiguouslyassignable identification of data carriers, valuable documents and/orpacks and the like, characterized in that the data carrier, the valuabledocument and/or the pack is provided with a coating which, by means ofits coloration or by means of the colour effect produced and/or by meansof its dimension and/or situation and/or its structure, permits anunambiguous assignment of the data carrier, of the valuable documentand/or of the pack to a defined property.
 2. Security elements forapplication to and/or for at least partial embedding in data carriers,valuable documents and/or packs and the like, characterized in that thesecurity elements are provided with a coating as security feature which,by means of its coloration or by means of the colour effect producedand/or by means of its dimension and/or situation and/or its structure,permits an unambiguous assignment of the data carrier, of the valuabledocument and/or of the pack to a defined property.
 3. Security elementsaccording to claim 2, characterized in that the coating is applied bymeans of a PVD or CVD process.
 4. Security elements according to claim2, characterized in that the coating consists of metals, their compoundsor their alloys.
 5. Security elements according to claim 2,characterized in that the coating consists of Al, Cu, Fe, Ag, Au, Cr,Ni, Zn, Cd, Bi, TiO₂, Cr oxides, ZnS, ITO, Bi oxide, ATO, FTO, ZnO,Al₂O₃, Zn chromate, Fe oxides, CuO, Cu—Al alloys, Cu—Zn alloys, ironalloys, steel, colour pigments, azurite or malachite and the like. 6.Security elements according to claim 2, characterized in that thesecurity elements have further functional and/or decorative layers. 7.Security elements according to claim 6, characterized in that theyadditionally have one or more electrically conductive layers and/orlayers with magnetic properties and/or layers with structures active indiffraction and/or layers with positive or negative printing. 8.Security elements according to claim 2, characterized in that they areprovided with a protective varnish layer on one or both sides. 9.Security elements according to claim 8, characterized in that theprotective varnish layer is pigmented.
 10. Security elements accordingto claim 2, characterized in that the security elements are laminated toone or more carrier substrate(s) which has/have the possibly functionaland/or decorative layers.
 11. Security elements according to claim 10,characterized in that the lamination adhesive is pigmented.
 12. Securityelements according to claim 2, characterized in that the securityelements are provided on one or both sides with a hot-melt or cold-sealadhesive or a self-adhesive coating.
 13. Security elements according toclaim 12, characterized in that the adhesive or the self-adhesivecoating is pigmented.
 14. Thin sheet material, characterized in that itis provided with a coating which, by means of its coloration or by meansof the colour effect produced and/or by means of its dimension and/orsituation and/or its structure, permits an unambiguous assignment to adefined property.
 15. Thin sheet material according to claim 14,characterized in that the coating is applied by means of a PVD or CVDprocess.
 16. Thin sheet material according to claim 14, characterized inthat the coating consists of metals, their compounds or their alloys.17. Thin sheet material according to claim 16, characterized in that thecoating consists of Al, Cu, Fe, Ag, Au, Cr, Ni, Zn, Cd, Bi, TiO₂, Croxides, ZnS, ITO, Bi oxide, ATO, FTO, ZnO, Al₂O₃ Zn chromate, Fe oxides,CuO, Cu—Al alloys, Cu—Zn alloys, iron alloys, steel, colour pigments,azurite or malachite and the like.
 18. Thin sheet material according toclaim 14, characterized in that the thin sheet material has furtherfunctional and/or decorative layers.
 19. Thin sheet material accordingto claim 18, characterized in that the thin sheet material additionallyhas one or more electrically conductive layers and/or layers withmagnetic properties and/or layers with structures active in diffractionand/or layers with positive or negative printing.
 20. Thin sheetmaterial according to claim 14, characterized in that the thin sheetmaterial is provided with a protective varnish layer on one or bothsides.
 21. Thin sheet material according to claim 20, characterized inthat the protective varnish layer is pigmented.
 22. Thin sheet materialaccording to claim 14, characterized in that the thin sheet material islaminated to one or more carrier substrate(s), which possibly has/havefunctional and/or decorative layers.
 23. Thin sheet material accordingto claim 22, characterized in that the lamination adhesive is pigmented.24. Thin sheet material according to claim 14, characterized in that thethin sheet material is provided on one or both sides with a hot-melt orcold-seal adhesive or a self-adhesive coating.
 25. Thin sheet materialaccording to claim 24, characterized in that the adhesive or theself-adhesive coating is pigmented.
 26. Valuable documents, packs andthe like which have a security element according to claim
 2. 27. Use ofthe security elements according to claim 2, if appropriate followingtailoring, as security features in data carriers, in particular valuabledocuments such as identity papers, cards, banknotes or labels, seals onor as packaging material, for example in the pharmaceutical, electronicand/or foodstuffs industry, for example in the form of blister films,folding boxes, covers, film packs.
 28. Use of the thin sheet materialaccording to claim 14, if appropriate following tailoring, as securityfeatures in data carriers, in particular valuable documents such asidentity papers, cards, banknotes or labels, seals on or as packagingmaterial, for example in the pharmaceutical, electronic and/orfoodstuffs industry, for example in the form of blister films, foldingboxes, covers, film packs.
 29. Use of the system according to claim 1for colour identification of the value or other properties of a valuabledocument, of a product and/or of a pack.
 30. Valuable documents, packsand the like which have a system according to claim 1.